The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory captions and links exemplifying features within the Earth system. The community is invited to contribute digital imagery, short captions and relevant links.

Moon Trails

The photo above showing a strangely creased full Moon was captured just after 10 p.m. on December 31, 2009 near Athens, Greece. These tracks have nothing to do with the partial lunar eclipse that was in progress. Rather, the explanation is much more down to Earth (almost): the lines are condensation trails (contrails) from a jet aircraft. The hiccup in the tracks of the contrails is a result of wind shear aloft. At the altitude contrails form, above about 20,000 ft (6,084 m), air currents and jet stream winds can be quite vigorous. If the winds are moving at a constant velocity and a constant direction, the contrails will maintain their shape and separation; however, if this is not the case, they’ll quickly become deformed and distorted.